Dr Shah was one the key forensic investigators in 'Kharotabad Massacre'.

Masked motorcycle riders ambushed him while he was on his way home.

After intercepting him, assassins shot him in the head five times and fled the scene, police said.

He was rushed to the hospital but to no avail, as doctors confirmed he had died before even he was brought into the emergency room.

Shah had spoken about death threats from unknown people in a televised press conference earlier this year after he resisted pressure to fudge the postmortem reports of four unarmed Russians and a Tajik shot dead by police.

On May 17, police and Frontier Corps paramilitary forces opened fire on the group, saying they were suicide bombers who attacked a checkpoint in Kharotabad on the outskirts of Quetta.

A subsequent judicial commission found that the Tajik and the Russians, three of whom were women and one of whom was pregnant, were unarmed. It sacked two police officials over the killings.

Balochistan is gripped by a regional insurgency for self-determination. It is also a flashpoint for Taliban and sectarian violence.